DESCRIPTION: The Behavioral Science Core has two objectives: to enhance the integrity of the independent variables of research involving human subjects (especially children and youth) where cooperation (compliance, adherence) represents a serious confound or barrier; and to expand the range and type of dependent variables by making available state-of-the- science methods so that investigators can objectively quantify behavioral phenomena specific to mental retardation and related disorders and identify, track and compare cognitive, behavioral, and developmental characteristics of genetic phenotypes, syndromes, diagnoses, intervention approaches, and animal models. The first objective is achieved by antecedent stimulus control procedures and contingency shaping procedures; the second by selection and use of standardized assessment procedures, direct observation techniques, and computer performance tasks designed to assess psychological variables.